Covers for top-charged furnaces



y 7, 1957 J. M. GUTHRIE 2,791,191

COVERS FOR TOP-CHARGED FURNACES Filed March 50, 1954 2 Sheets-Sheet 1 1 M IN V EN TOR.

JAMES M. GUTHRIE.

1 BY I flafijwhmdmhd ATTORNEYS.

May 7,1957

CHARGED FURNACES 2 Sheets-Sheet 2 Filed March 50, 1954 INVENTOR. JAMES M. GUTHRIE.

BY I H au MMM/ M/ Q um 1 k I \m w m w z Y Q 1? w? n ATTORNEYS.

covnus FOR TOP-CHARGED FURNACES James M. Guthrie, Crafton, Pa., assignor to Loftus Engineering Corporation, Pittsburgh, Pa., a corporation of Maryland Application March 30, 1954, Serial No. 419,804

2 Claims. (Cl. 110-473) This invention relates to pit-type furnaces, sometimes referred to as soaking pits. More particularly, the invention relates to such furnaces for heating and soaking steel ingots, preparatory to rolling, or forging, or the like, and the invention consists in certain new and useful improvements in the construction of the removable covers of such pit furnaces.

It will be understood that a soaking pit cover comprises a steel frame that supports a suspended or sprung arch of refractory material that in service is exposed to the heat of the furnace chamber beneath it. The steel frame carries a depending sealing member around its periphery, and this member, ordinarily formed by a continuous series of cast-steel shoes or blades, is lodged in a trough of sand that extends continuously around the open top of the furnace chamber. The sealing element, embedded as it is in the sand, peripherially seals the cover upon the top of the furnace chamber. The periphery of the steel frame of the cover is formed of steel beams or steel slabs integrated end to end, each beam or slab having the major axis of its section arranged vertically, and it is to the lower edge of such peripheral frame that the sealing blades are secured, to extend into the sand, as said. Under the effect of the intense heat developed in the furnace during operation, the lower edge of the peripheral steel frame of the cover becomes hotter than its upper edge, with the result that the steel frame is caused to bow upwardly, making it difficult to obtain and maintain the desired sealed engagement of the cover with the top of the furnace.

It is the object of my invention practically to eliminate such bowing of the steel frames of soaking pit covers.

An exemplary embodiment of the invention is illustrated in the accompanying drawings, in which:

Fig. 1 is a view in plan of a typical steel frame of a cover for a pit furnace. The cover is rectangular as viewed in plan, but it will be understood that the frame may be square or round to suit the particular form of the top of the furnace. To avoid interference with the signature on the drawing a portion of the frame is broken away at the lower left-hand corner;

Fig. 2 is a view of the cover, partly in side elevation, as seen from the right of Fig. 1, and partly in vertical section;

Fig. 3 is a view of the cover in cross section, as seen on the plane Ill-4H of Fig. 1;

Fig. 4 is a fragmentary enlarged view of one corner of. the cover, as seen from the right of Fig. 2; and

Fig. 5 is a fragmentary view of one of the side l-beam frame members of the cover, showing in vertical section the structure of the sealing blades used with the cover.

Referring to the drawings, the furnace cover is in exemplary Way shown as rectangular in plan (Fig. 1), and the refractory body of the cover is constructed as a flat or suspended arch (Figs. 2-4).

The frame of the illustrated cover is formed of two longitudinal peripheral side members 2 and 3 and peripheral end members 4 and 5. These side and end memnited States Patent '0 bers may be formed of heavy l-beams or of elongate slabs of steel arranged with their major axes vertical. In the present case, the members are formed of I-beams, and it is to be noted that the side members 2 and 3 are extended at the opposite ends of the cover in portions 6. When the cover is positioned upon the top of a furnace the portions 6 rest upon supporting stools 7 (Fig. 2) provided on the furnace body (not shown).

At suitably spaced points in the length of the frame, cross l-beams 8 of less vertical dimension than the side and end beams 2-5 are provided, and at the two ends of the frame two of the cross I-beams (8a) are closely spaced from the peripheral frame members 4 and 5 and integrated thereto by vertical I-beam sections 812, as shown in Figs. 1 and 2. The cross I-beams 8 and 8a are medially reinforced by a line of I-beam sections 9, and diagonal braces 10 are provided on the top of the beam assembly. At four points in the frame lifting lugs 11 are provided for engagement by the usual cover carriage that lifts and removes the cover from service position, to give access to the furnace for charging and removing ingots, and for then returning the cover to service position. The lifting lugs 11 are secured to paired channels 12 extending between two sets of the cross i-beams d, as shown in Fig. 1. Along the lower edges of the cross lbeams 8 and 8a appropriately spaced longitudinally extending hanger beams 13 are secured. The several structural steel members described are secured and integrated, by welding in this case, giving a sturdy reinforced steel framework for the support of the refractory arch of the cover.

The refractory arch is constructed of hanger blocks 14, attached to the hanger beams 13 by means of metal clips 15, and intervening suspended blocks 16. The blocks 14 and 16 are constructed of a suitable burned firebrick, and the surfaces of the blocks are formed with. complementary tongues and grooves, whereby the entire block assembly is interlocked and suspended by the clips 15 engaged to the hanger beams 13.

At the opposite ends of the cover are mounted heat shields 17 (Figs. 1 and 2) formed of a suitable insulating material, to protect the steel beams 4 and 5 from the intense heat of the furnace when the cover is removed, it being understood that the cover, when lifted from sealed position on the furnace, is moved endwise in one direction or the other from over the open top of the furnace.

Around the periphery of the cover a continuous series of sealing blades 18 of cast iron or steel is suspended from the bottom of the I-beam members 2, 3, 4 and 5 that form the rectangular or peripheral frame portion of the cover. As shown in Fig. 5, each sealing blade comprises a horizontal top flange portion 19 that bears against the bottom of the basal flange of the l-beam frame member to which the blade is secured, and bolts 20 secure the blade to said basal flange. Extending downwardly from the flange portion 19, the blade includes two vertical blade portions 21 and 22 horizontally offset from one another and interconnected by a horizontal portion 23. The several portions of the blade structure are reinforced by vertical webs 24 and 25 integrally cast with the rest of the blade structure. On the inside of the vertical blade portion 21 is an outstanding rib portion 26 that in the assembled series of blades on the cover provides an internal peripheral flange which fits in appropriate grooves formed in the outer peripheral row of suspended blocks (16a) in the refractory arch carried by the cover frame, and this peripheral flange (26), in conjunction with the ad jacent hanger blocks 14, insures security of the said peripheral blocks 16a.

Referring particularly to Fig. 5, it Will be understood that, when the continuous series of blade members 18 has been installed around the rim of the cover, with suflicient clearance for expansion between the successive blade members in the series, an inside and outside protection of plastic refractory material is tamped in place, as indicated in section at 27 and 28, respectively. The blade members are provided with studs 29 and with bottom ledges or shoulders 30 to secure the plastic refractory material in installed position. When the cover is placed in service, the heat of the furnace vitrifies and integrates the refractory material, thereby providing a hard thermal protection for the vulnerable portions of the sealing blade assembly. During the installation of the plastic refractory material suitable expansionjoints are included in the material in its extent around the periphery of the cover. It is such continuous refractory-faced blade structure that is embedded in the continuous channel of sand around the mouth or horizontal doorway of the furnace, whereby the cover is sealed in closed position upon said furnace.

In accordance with my invention the basal flanges 31 of the members (2-5), which form the peripheral support or mainframe portion of the cover, are cut or slit, as by means of an oxygen torch, at spaced points C. In the case of the cover of the elongate rectangular form herein illustrated it is suflicient if only the two side I- beam members 2 and 3 are slit, as shown, although in the case of a square or a circular cover the slits may be provided around the entire periphery of the cover. The slits preferably go all of the way through the basal flanges 31 of the members 2 and 3, and extend through the vertical Webs 32 of such members up to the points D that are substantially level with the bottoms of the cross beams 8 and 8a. The cross beams 8 and 8a, as well as the hanger beams 13 secured thereto, are vertically spaced from the top of the refractory arch 14, 16 by such an interval that the heat of the furnace does not cause objectionable distortion of the steel framework of the cover.

Adjacent to the tops D of the slits C formed in the bottom portions of each of the peripheral frame members 2 and 3 is a beam-reinforcing member 33 welded to and extending along the length of the outer or exposed face of the vertical web 32 of the frame member, and to the inner face of such vertical web, in the intervals between the cross beams 8 and 8a, reinforcing members 34 are welded. The reinforcing members 33 and 34 may comprise, as they are herein shown, heavy structural steel angles, although it is contemplated that channels, or structural steel of other shape having horizontal flange portions may be used for the purpose. With such reinforcement, or its equivalent, the peripheral or main frame members 2 and 3 are adequate to support the loads imposed upon them in service. As the basal flange or beam portions 31 and lower portions of the webs 32 of the said peripheral or main frame members expand under the effect of radiated and conducted furnace heat the slots (C) allow free expansion of such portions of members 2 and 3, in consequence whereof the objectionable bowing or distortion of the steel framework of the cover is avoided.

It will be perceived that the effective load-bearing section or body of each of the main frame members 2 and 3 comprises the top flange 35, the vertical web 32 between the top. flange 35 and the tops D of the slits C, and the two angles 33 and 34. The frame members 2 and 3 are designed for load accordingly. After the bottom beam portion of each of beams 2 and 3 has been slotted or slit as described, the portion of the vertical web 32 below the angles 33 and 34 and the basal flange 31 form in effect (by reason of the slots C) a series of beam sections depending from the load-bearing section or body the beam (3235), and the primary if not the only functions of these depending beam sections are to carry the sealing blade assembly 13-30, and to safeguard the main beam body from objectionable thermal distortion. At suitable points E longitudinally of the beams 2 and 3 gussets 36 of steel plate are welded, and these gussets reinforce the portions 32, 33 and 35 of the main beam body, as well as the depending portions of the web 32 and basal flange 31 below the angles 33 and 34.

It may be noted that, while the bodies of the sealing blades Iii-30 may straddle or span the slots C, no two of the bolts 20 of any one blade will be used on opposite sides of a straddled slot in such way as to preclude the ready expansion of the steel which the slot is intended to accommodate.

The soaking pit cover described is safeguarded against objectionable thermal distortion, and it will be understood that many variations and modifications in the structure disclosed are permissible within the spirit of the invention defined in the appended claims.

I claim:

1. In a pit furnace cover comprising a peripheral main frame of steel members arranged end to end, each with the major axis of its cross section arranged vertically, an arch of refractory material supported by, and within the compass of, said main frame, and a series of sealing blades arranged peripherally of and below said frame members for the provision of a substantially continuous sealing blade structure throughout the periphery of said cover, said sealing blades being arranged end to end but with sufficient clearance between them for expansion peripherally of said main frame members under the elfect of the heat to which the structure is exposed in service;

the invention herein described comprising a series of beam portions extending peripherally of said frame and arranged vertically between the expansible'sealing blade structure and the main body portions of said main frame members, said beam portions in the series being spacedapart by upwardly extending slots, whereby said beam portions may under the effect of heat expand with said sealing blade structure without undue distortion of said main frame, and continuous longitudinally extending horizontal flange portions that are integral with said main frame members at the tops of said slots between said beam portions, said horizontal flange portions being positioned above the adjacent periphery of the arch of refractory material.

2. The structure of the preceding claim, wherein said beam. portions are formed integrally with the bodies of said main frame members, and wherein said longitudinally extending horizontal flange portions above the arch of refractory material are welded to said main frame members at the tops of the slots.

References Cited in the file of this patent UNITED STATES PATENTS 2,444,736 Hazen July 6, 1948 2,539,421 Higgins Jan. 30, 1951 2,657,651 Forsyth Nov. 3, 1953 

